/Engine/Source/Runtime/GeometryCore/Public/Selections/MeshConnectedComponents.h
Find all connected vertex components that contain one or more Seed Vertices and store in Components array. Search only starts from Seed Vertices.
void FindVerticesConnectedToSeeds ( const [TArray](API\Runtime\Core\Containers\TArray)< int > & SeedVertices, [TFunction](API\Runtime\Core\GenericPlatform\TFunction)< bool(int32, int32)> VertsConnectedPredicate )